September 26, 2011

The rolling bits

I’ve been working on “Imran’s better bot” for a couple of weeks now. It will, in the end, have some neat twists. The design is meant to be modular, and support some major uses — milling, a couple of different types of printing, and surfacing. It’ll also be a very easy build — I’m shooting for 1 hour for an experienced person, and less than 4 for a total newbie.

I had originally planned on slide bearings — and I still may have those in the end, but I’ve got a core problem with slide bearings. I can’t build them without a CNC mill to begin with. I’ve tried printing slide bearings using PLA — and it wants to work. But printed bearings just don’t work — the “layer lines” typical in printed parts work like traction pads on tires — meaning that all non-planar forces cause binding. So, I’m forced to go to a a more complex design — a rolling chassis.

I’m proud to say, I’ve got a working rolling chassis! It rolls beautifully, and handles torsion forces well. With this section, the first major problem is temporarily overcome.

It may not work in the long term — I’m worried about flakes and shaving causing problems when used as a mill for a very long time — but for my first version, it’ll work great. Once I get my first bot built, I’ll examine building a slide bearing, or perhaps a hybrid bearing( which was my original idea. ), for handling gantry movement.